Golden does not make a water-based topcoat appropriate for the architectural market. Instead, we recommend testing and using products that are readily available at good paint and coatings retail outlets.

In the world of art materials, a “varnish” is a clear protective coating that may be removed by some means (usually with strong chemicals) in order to access the original surface of the painting so that conservation work may be done. In so doing, scratches, light damage and soils are removed with the varnish.

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In contrast, a “topcoat” usually describes a clear protective coating that is permanent, and is more commonly used in architectural applications to protect faux wood graining, marbling, and mural work, or to unify the sheen of a decorative finish. The large surfaces involved with architectural-scale jobs makes the removal of a varnish a time-consuming and unpleasant task. Architectural surfaces that are not excessively weathered or worn can be maintained and restored simply by re-applying the topcoat on a periodic maintenance schedule. The frequency will depend on the severity of the service environment.

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Topcoats [http://proceedsystem.com/wiki/index.php/Category:Clear_Acrylic_Topcoat Proceed® Clear Acrylic Topcoats (Gloss & Matte)] are permanent clear topcoats that utilize exterior-grade polymers, and so are suitable for both interior and exterior applications. The Gloss and Matte topcoats may be blended in any ratio to produce the desired sheen.

Current revision as of 12:32, 12 March 2015

Contents

Topcoats and Varnishing (Definition):

Varnishes and topcoats serve to protect a painting, mural or wall coating against dirt, dust, humidity and ultra violet rays. Varnishes and Topcoats can extend the life of a painted wall and, depending on the topcoat, can allow for a light cleaning to a heavier scrubbing. A removable varnish, like MSA Varnish or Hard MSA Varnish, is a good option for a mural or other painted areas that will want to be preserved for extended periods of time. The purpose of the removability is for the varnish to endure all the abuse you do not want the painted area to receive. If need be it can be removed, recoated and the painting will look the same as the day it was finished. Removable varnishes are softer than their permanent counterparts and have a greater probability of marring, scratching or damage. A topcoat, such as Polyurethane, on the other hand, is a permanent coating that offers a greater physical barrier against the elements, is harder, more durable and can endure washing and scrubbing without damaging the finish. Aliphatic (non-aromatic organic compound) polyurethanes are much more user-friendly than their older aromatic versions and have less of a tendency to yellow.
Please click this link to view the Technical Data Varnish Sheet

Varnish Descriptions

MSA (Mineral Spirit Acrylic) Varnish can be used over water-based or oil-based paints and used in both interior and exterior applications. MSA Varnish is available in Gloss, Satin or Matte sheens, is removable and can be brush or spray applied. MSA should not be used in applications in which rain or snow can collect on the surface, polyurethane or automotive clear coat should be used in such situations. A harder version of the MSA, called Hard MSA, is available as a Golden custom product when a more durable but still removable finish is required. Hard MSA will protect to a greater extent than the MSA against scratching and marring but involves a more difficult removal. When using MSA, Hard MSA or other top coat over alkaline surfaces, such as cement, testing should be preformed to insure compatibility between the surface and coating.

MSA Varnish

Polymer Varnish is removable, water based and is available in Gloss, Satin or Matte. Polymer Varnish can only be used in interior applications and only over water based media. While it does offer protection from dirt, dust, humidity and ultra violet rays, Polymer Varnish does not offer as much protection or durability as the MSA Varnish.

Polymer Varnish

Varnish Sheens

Gloss varnish offers the best physical protection and ability to be lightly cleaned due to its slick surface quality. The different sheens of varnish can be mixed with one another to achieve a very specific desired sheen not offered in the three choices available. To achieve a satin sheen with gloss and matte varnish that is comparable to our available satin sheen mix one part gloss to two parts matte.

Isolation Coat

Often it is recommended to coat the painting with an isolation coat before varnishing. An isolation coat is a permanent clear coating that serves to protect the painting if the varnish is ever removed and also creates an even surface on which to varnish. For a brushable isolation coat gently mix 2 parts Soft Gel Gloss to 1 part water and apply with a soft brush. For a sprayable isolation coat mix 2 parts GAC 500 to 1 part Airbrush Transparent Extender.
Please click this link to view the Technical Data Sheet for Isolation Coat.

Top Coats

In the world of art materials, a “varnish” is a clear protective coating that may be removed by some means (usually with strong chemicals) in order to access the original surface of the painting so that conservation work may be done. In so doing, scratches, light damage and soils are removed with the varnish.

In contrast, a “topcoat” usually describes a clear protective coating that is permanent, and is more commonly used in architectural applications to protect faux wood graining, marbling, and mural work, or to unify the sheen of a decorative finish. The large surfaces involved with architectural-scale jobs makes the removal of a varnish a time-consuming and unpleasant task. Architectural surfaces that are not excessively weathered or worn can be maintained and restored simply by re-applying the topcoat on a periodic maintenance schedule. The frequency will depend on the severity of the service environment.

Topcoats Proceed® Clear Acrylic Topcoats (Gloss & Matte) are permanent clear topcoats that utilize exterior-grade polymers, and so are suitable for both interior and exterior applications. The Gloss and Matte topcoats may be blended in any ratio to produce the desired sheen.

VOC’s and Wall Coatings

Any paint or topcoat applied to a building, including interior or exterior walls, is considered an architectural coating and subject to regulations limiting the amount of VOC’s (Volatile Organic Compounds) a product may have. Murals painted directly onto these surfaces, therefore, will fall under the same guidelines and all paints, mediums, and varnishes being used will need to comply with the same rules. Containers that are 1 Liter (1.05 Quarts) or less in size, however, are currently exempt from these requirements.

Topcoating Slow Drying Materials

Topcoating or varnishing slow drying products will require a quick test to determine if the coating is still water-sensitive. If not, bleeding, smearing or streaking can occur. Products such as Slow Drying Fluid Acrylics or Acrylic Glazing Liquid can remain water-sensitive for a period of time once they have dried. Creating a test panel of similar composition to the application done at the same time will allow you to test for water-sensitivity without damaging the work done. Using the test panel or an inconspicuous area of the work done, take a cotton swab wetted with water and gently rub in a circular motion. If you witness a color or glaze removal then allow for more time to dry before a topcoat or varnish is applied. Accelerating the drying process can be done by circulating the air in a room with a fan or other form of dry air. Heat can sometimes cause surface defects and can soften a film and is not advisable for accelerating drying.